Switch actuating apparatus utilizing a reciprocal rod with helical grooves to impart rotational movement to cams



Dec. 17, 1968 e. A. NORWOOD 3,417,218

SWITCH ACTUATING APPARATUS UTILIZING RECIPROCAL ROD WITH HELICAL GROOVES TO IMPART ROTATIONAL MOVEMENT TO CAMS Filed Jan. 11, 1967 2 Sheets-Sheet 1 N I r r GLEN A. NORWOOD s q A INVENTOR.

ATTORNEYS Dec. 17, 1968 3,417,218

SWITCH ACTUATING APPARATUS UTILIZING A RECIPROCAL ROD G. A. NORWOOD WITH HELICAL GROOVES TO IMPART ROTATIONAL MOVEMENT TO CAMS 2 Sheets-Sheet 2 Filed Jan. 11, 1967 GLEN A. NORWOOD I INVENTOR.

BY [a ATTORNEYS United States Patent SWITCH ACTUATING APPARATUS UTILIZING A 'RECIPROCAL ROD WITH HELICAL GROOVES TO IJVIPART ROTATIONAL MOVEMENT T0 CAMS Glen A. Nor-wood, Kent, Wash. 98031 Filed Jan. 11, 1967, Ser. No. 608,591 15 Claims. (Cl. 200-153) ABSTRACT OF THE DISCLOSURE Apparatus for moving and accurately positioning an element such as a cutter head, machine tool or the like in a predetermined position by hydraulic power. An electrical switching unit is mechanically linked to the piston rod of a hydraulic cylinder for performing a programmed switching operation determined by a manually set selector switch and the position of the piston rod. The piston rod is mechanically connected to a control rod which includes helical cam grooves. Linear movement of the control rod is used to operate multiple switch operating cams. The cams are in the form of disk members so mounted as to be rotatable relative to each other for adjusting the extent of the cam lobes carried thereby. Selector switches in the electrical circuit determine a set position at which the piston of the hydraulic cylinder will stop and hold when a cam switch is operated. The control rod is provided with two helical cam grooves with the follower means comprising spring pressed ball detents mounted in a surrounding tubular sleeve. The detents are caused to follow the grooves as the rod is reciprocated and are located a very slight distance ofi' center so as to bear on one side of the grooves. The off center positioning of the ball detents eliminates back lash and provides for accurate positioning of the piston rod since little or no play is normally allowed between the control rod and the surrounding tubular sleeve which mounts the switch operating cam disks.

Background of the invention The present invention relates in general to hydraulic positioning apparatus and more particularly to an improved control and switching system wherein accurately determined set positions for the piston rod of the hydraulic cylinder can be provided. The present invention provides improvements over the prior art in the nature of making it possible to easily adjust the set position within a given range of travel of the piston rod and by eliminating lost motion in a mechanical system to obtain a high order of accuracy.

Accordingly the primary object of the present invention is to provide an improved hydraulic and electrical positioning system for the positioning of elements such as cutter tools and the like which is implified in structure and highly efficient and versatile in its operation.

Another object of the present invention is to provide a system of the character described wherein the linear motion of a control rod is translated into rotary motion for driving switching cams to control the set position of the piston rod of a hydraulic cylinder.

Another object of the invention is to provide a hydraulic and electric positioning unit of the character described wherein lost motion in a mechanical linkage is eliminated so as to enable more accurate positioning.

Other and more particular objects and advantages of the invention will be apparent to those skilled in the art from the following specification and appended claims and from the accompanying drawings wherein:

Brie] description of the drawings FIG. 1 is a partially sectioned end elevational view of the hydraulic cylinder and control device;

FIG. 2 is a cross sectional view taken along lines 22 of FIG. 1;

FIG. 3 is a cross sectional view taken along lines 33 of FIG. 2;

FIG. 4 is an elevational detail showing a portion of the control rod mounting; and FIG. 5 is a schematic of the hydraulic and electrical circuits.

Description 07 the preferred embodiments The present system comprises a hydraulic cylinder or power unit, a cam operated switching unit mechanically linked to the piston rod of the cylinder and a fluid system including a three position valve, solenoid valve operators and an electrical switching system. The hydraulic cylinder may be utilized for a multitude of different applications such as positioning a cutter head, machine tools of all types or any other application where precise positioning of a member is required.

Referring to FIGS. 1 and 2, a conventional hydraulic power unit comprising the cylinder 1 and piston rod 2 is shown as being provided with an upstanding arm or plate 3 rigidly connected to the piston rod. The arm 3 is connected to one end of the control rod 4 which extends rearwardly and passes through the control unit indicated generally at 6 mounted on the top side of the cylinder 1. It will be understood that the rod 4 is rigidly connected to the arm 3 and thus reciprocates in either direction with the piston rod 2.

The control unit 6 has a housing which may be varied in configuration and, in the present instance, comprises the front and rear end plates 7 and 8, respectively, the base plate 9, dust cover 11 and side walls 12 and 13. The housing may be assembled by means such as welding or bolting and serves to house the rotatable cam disks presently to be described.

As seen in FIG. 2, the control rod 4 is provided with a cylindrical sleeve or control tube 13 through which the rod reciprocates. The control tube 13 is journaled for rotation by anti-friction bearing means 14 mounted in the front end plate 7 and a second anti-friction bearing means 16 mounted in the rear end plate 8. The bearing means 14 and 16 may constitute ball bearing units or any other anti-friction bearing means which allows free rotation of the tube 13 and prevents longitudinal movement. A retaining plate 17 is fitted to the end plate 7 and has wiper means or the like 18 which surrounds the control rod 4. A similar retaining plate 19 is fitted to the end plate 8 and mounts a tubular housing 21 which extends rearwardly therefrom and protects the protruding end of the control rod 4.

As illustrated in FIGS. 2 and 3, the rod 4 is provided with first and second helical grooves 22 and 23 of circular cross section which are located in diametrically opposed positions on the rod. The grooves 22 and 23 extend over the major portion of the rod 4 and are engaged by ball detents 24 and 26 respectively, which are located in the associated bushings 27 and 28 mounted in the wall of the control tube 13. The balls 24 and 26 are backed by the spring members 29 and 31 respectively so as to be biased into the grooves 22 and 23. As seen most clearly in FIGS. 3 and 4, the centers of the bushings 27 and 28 are off-set from a plane passing through the longitudinal center lines of the grooves 22 and 23 so as to locate the balls slightly off center from the grooves. The offset distance will normally be only a few hundredths of an inch with the balls being biased against adjacent sides of the grooves 22 and 23, it will be noted that no play or lost motion is permitted between the rod 4 and control tube 13. This feature prevents any backlash or over travel of the rod thus providing for precise switching responsive to the positioning of the rod and tube.

Referring especially to FIG. 2, the control tube 13 mounts a plurality of longitudinally spaced pairs of cam disks for performing the switching function. The disks, one pair of which is indicated at 32 and 33 may be fiat circular members with a cam lobe extending over a substantial portion of the peripheral edge as illustrated in FIG. 1. The disks may be made from plastic or any other dielectric and are mounted on individual hubs 34 which are stacked in abutting position along the length of the control tube 13. The right end hub 34 as viewed in FIG. 2 is held by a snap ring 36 carried on the tube 13 and the opposite end of the series of hubs is held by the screw threaded member 37. The hubs may be keyed to or otherwise'prevented from rotation on the tube. Each hub is provided with a fixed flange 38 and a gland nut 39 for applying pressure to a friction washer or the like 41 to hold the disks in an adjustably fixed face-to-face position. The washers 41 may be keyed to the hubs to prevent relative rotation. With this arrangement the relative rotational position of each disk on the hub may be adjusted so as to lengthen or shorten the extent of the cam lobe provided by the combined lobes of the disk pairs.

Also mounted within the housing 6 is a bank of .microswitches 42 having operating arms 43 with roller followers 44 which are contacted by the cam lobes of the disks. The rollers are of a suitable width so as to contact the surface of both disks of the respective pairs of disks.

Referring now to the schematic in FIG. 5, a typical positioning system utilizing five sets or positions to which the piston rod may be caused to move and come to a hold position will be explained. The system will include the cylinder 1 having its piston rod 2 which is caused to move in either direction or to come to a hold position by means of the four way valve 46. The valve 46 is a three position valve shown in the center position in which the piston rod is locked in position since both cylinder ports are blocked. The valve spool is shifted to the right by energizing the A solenoid and is moved to the left by energizing the B solenoid. Energizing the A solenoid admits pressure to the right end of the cylinder to move the piston rod outwardly and energizing the B solenoid admits pressure to the left end of the cylinder to return the piston rod. Five selector switches S1 through S are provided in the electrical circuit which correspond to the five desired set positions for the piston rod. The cam switches for energizing the A solenoid are indicated at A1 through A4 and the cam switches for energizing the B solenoid are indicated at B2 through B5. For ease of illustration, the same cam disk is shown as operating both an A and a B cam switch. In practice separate cam disks would normally be utilized for A and B switches. The cylinder is illustrated in the number 3 set position in FIG. 5 which has been accomplished by manually closing the S3 selector switch which allows the piston rod to be moved to the number 3 position before the cam disk opens both cam switches A3 and B3. With both of these switches open, the valve 46 is allowed to return to its center position with both ports of the cylinder being locked. To move the piston rod from the number 3 position shown to the number 2 position for example, the S3 selector switch would be opened and the S2 selector switch closed. Since A2 cam switch is in the closed position, closing the S2 selector switch energizes the A solenoid and pressurizes the right end of the cylinder 1. The piston rod accordingly moves outwardly and, when it reaches the number 2 set position the cam lobe on the disk associated with the A2 cam switch will contact the A2 switch arm and open the A2 switch. Because of the cam lobe position the B2 cam switch will be held in the open position. Since both A and B cam switches are open the valve is allowed to center and the cylinder locked.

It will be noted that the A cam switches numbered less than 3 will be closed in the present position of the piston rod and therefore the closing of any selector switch numbered less than 3 would complete the A solenoid circuit driving the piston in the outward direction to the desired set. In a like manner, all B cam switches number greater than 3 are closed so the appropriate switch would complete the B solenoid circuit to drive the piston in the in direction of the desired set. Upon reaching any given set position, both A and B cam switches are opened thus allowing the valve 46 to return to the center position and lock the cylinder.

From the foregoing it will be apparent to those skilled in the art that the present invention provides significant improvements in hydraulic and electrical positioning apparatus of the character described. The arrangement and types of structural components utilized within the invention may be subject to numerous modifications well within the purview of this invention and applicant intends only to be limited to a liberal interpretation of the specification and appended claims.

Having thus described the invention what is new and desired to be secured by Letters Patent is:

1. Control apparatus for actuating switches at predetermined points along the course of lineal travel of a motor member comprising; a control rod connected for linear movement with said member, cam means on said rod, a rotatably mounted control tube adapted to slidably receive said rod, follower means carried by said tube and adapted to engage said cam means, whereby linear movement of the rod is transformed into rotational movement of the tube, and a plurality of switch actuating cams carried by said control sleeve.

2. The apparatus according to claim 1 wherein; said control rod is circular in cross section and said cam means comprises curvilinear groove means in the surface of said rod.

3. The apparatus acording to claim 2 wherein; each of said switch actuating cams comprises a pair of face-toface disk members mounted for individual rotary adjustment relative to said control tube, means to releasably hold said disks in any given position of rotation, and each of said disk members having a cam lobe extending over a substantial portion of the peripheral edge thereof, whereby the circumferential extent of the switch actuating cam provided by the combined adjacent cam lobes is readily adjustable.

4. The apparatus according to claim 2 wherein; said curvilinear groove defines a helix and said follower means comprises spring biased ball detent means mounted in said control tube so as to engage and follow said helical groove to produce rotation of said control tube as the ro is reciprocated in either direction.

5. The apparatus according to claim 4 wherein; each of said switch actuating cams comprises a pair of face-toface disk members mounted for individual rotary adjustment relative to said control tube, means to releasably hold said disks in any given position of rotation, and each of said disk members having a cam lobe extending over a substantial portion of the peripheral edge thereof, whereby the circumferential extent of the switch actuating cam provided by the combined adjacent cam lobes is readily adjustable.

6. The apparatus according to claim 4 wherein, a second helical groove is provided in the surface of said rod and second spring biased ball detent means is provided in said control tube to engage and follow said second groove, said first and second grooves being located at diametrically opposite positions on the surface of the rod and said ball detent means being offset in the same direction from a plane passing through the longitudinal center lines of said grooves, whereby lost motion between said rod and said tube is prevented.

7. The appartus according to claim 6, wherein; each of said switch actuating cams comprises a pair of face-toface disk members mounted for individual rotary adjustment relative to said control tube, means to releasably hold said disks in any given position of rotation, and each of said disk members having a cam lobe extending over a substantial portion of the peripheral edge thereof, whereby the circumferential extent of the switch actuating cam provided by the combined adjacent cam lobes is readily adjustable.

8. In combination with a motor having a member adapted for linear movement and an electrical circuit with cam switch means to control the movement of the member to a predetermined set position, set positioning control apparatus comprising; a control rod connected for linear movement by said member, cam means on said rod, a rotatably mounted control tube adapted to slidably receive said rod, follower means carried by said tube and adapted to engage said cam means, whereby linear movement of the rod is transformed into rotational movement of the tube, and a plurality of switching cams carried by said control tube for contacting said cam switch means at predetermined points along the course of travel of said member.

9. The combination according to claim 8 wherein; said control rod is circular in cross section, and said cam means comprises, helical groove means in the surface of said rod, said follower means comprising spring biased ball detent means mounted in said control tube so as to engage and follow said helical groove means to produce rotation of said control tube as the rod is reciprocated in either direction.

10. The combination according to claim 9 including; a second helical groove in the surface of said rod and second spring biased ball detent means is provided in said control tube to engage and follow said second groove, said first and second grooves being located at diametrically opposite positions on the surface of the rod and said ball detent means being offset in the same direction from a plane passing through the longitudinal center lines of said grooves, whereby lost motion between said rod and said tube is prevented.

11. The combination according to claim 10 wherein; each of said switch actuating cams comprises a pair of face-to-face disk members mounted for individual rotary adjustment relative to said control tube, means to releasably hold said disks in any given position of rotation, and each of said disk members having a cam lobe extending over a substantial portion of the peripheral edge thereof, whereby the circumferential extent of the switch actuating cam provided by the combined adjacent cam lobes is readily adjustable.

12. In combination with a fluid motor having a ram connected to advance and retract a movable element, set

positioning control apparatus for said motor comprising; a control rod connected for linear movement by said ram, cam means on said rod, a rotatably mounted control tube adapted toslidably receive said rod, follower means carried by said tube and adapted to engage said cam means, whereby linear movement of the rod is transformed into rotational movement of the tube, a plurality of switch operators mounted on hte control tube, and electrical control circuit means for controlling the operation of said motor, said circuit including switch means adapted to be contacted by said switch operators for conditioning said circuit to lock the motor in a rest position at a predetermined point along the course of travel of the ram.

13. The combination according to claim 12 wherein; said control rod is circular in cross section, and said cam means comprises helical groove means in the surface of said rod, said follower means comprising spring biased ball detent means mounted in said control tube so as to engage and follow said helical groove means to produce rotation of said control tube so the rod is reciprocated in either direction.

14. The combination according to claim 13 including;-

a second helical groove in the surface of said rod and second spring biased ball detent means is provided in said control tube to engage and follow said second groove, said first and second grooves being located at diametrically opposite positions on the surface of the rod and said ball detent means being offset in the same direction from a plane passing through the longitudinal center lines of said grooves, whereby lost motion between said rod and said tube is prevented.

15. The combination according to claim 14 wherein; each of said switch actuating cams comprises a pair of face-to-face disk members mounted for individual rotary adjustment relative to said control tube, means to releasably hold said disks in any given position of rotation, and each of said disk members having a cam lobe extending over a substantial portion of the peripheral edge thereof, whereby the circumferential extent of the switch actuating cam provided by the combined adjacent cam lobes is readily adjustable.

References Cited UNITED STATES PATENTS 2,832,858 4/1958 Tydeman 200-153.13 XR 2,960,580 11/1960 Aquillon 200153.13 XR 3,138,673 6/1964 Goetz 200-153.13 XR FOREIGN PATENTS 212,290 2/1924 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner.

US. Cl. X.R. 

